Stabilized polyamide composition

ABSTRACT

A polyamide composition containing a) 2-mercaptobenzimidazol, b) 2-mercaptobenzimidazol copper salt and/or organic acid copper salt and one or more magnesium compounds from the group c) 8hydroxyquinoline magnesium salt, magnesium salt of a) and an organic acid magnesium salt, is disclosed.

United States Patent Nishijima et al.

[ June3,-1975 STABILIZED POLYAMIDE COMPOSITION Inventors: Kiyoaki Nishijima; Atsuo Tanaka,

both of Mihara, Japan Assignee: Allied Chemical Corporation,

Petersburg, Va.

Filed: Jan. 30, 1974 App]. No.: 438,131

US. Cl 260/45.75 C; 260/18 N; 260/45.8 Int. Cl C08g 51/62 Field of Search 260/45.8 N, 45.75 C, 18 N References Cited UNITED STATES PATENTS 10/1966 Twilley 260/18 3,516,956 6/l970 Reedy et al 260/22 FOREIGN PATENTS OR APPLICATIONS 994,577 4/1962 United Kingdom Primary ExaminerV. P. Hoke Attorney, Agent, or F irmRichard A. Anderson [57] ABSTRACT 3 Claims, No Drawings l STABILIZED POLYAMIDE COMPOSITION BACKGROUND OF THE INVENTION This invention pertains to the polymer composition which is excellent for heat resistance, effective in drip prevention, and does not bring corrosion at all against polyamide manufacturing and treating equipment.

Polyamide, in general, is easily influenced by oxidation, and due to this oxidation, it has properties, particularly, at high temperatures, to lower molecular weight, create cross linking at times, and also changes easily its colorand properties.

To prevent such heat degradation, several heat degradation prevention methods were proposed in the past, for example, it has been known that when 2- mercaptobenzimidazol (below abbreviated to MBI) and copper compounds are added to polyamide, polyamide composition which is excellent to heat resistance is obtained. (Reference to British Pat. No. 945,186). However, conventional copper compounds, for instance, chloride copper, or bromide copper were used in combination with MBI, due to their correlation effect, the corrosion on various polyamide manufacturing and treatment equipment becomes severe, in particular, in case polyamide is nylon 6, the effect is greaterduring leaching process, and the compounds could notbe used in practice, or were used knowing the necessity for repairs and replacement.

Moreover, even though MB] and copper compound mixture improves heat resistance, it provides insufficient spinnability, extremely susceptible to drips, reduces rate of production, also lowers its draw ratio and invites worse drawn yarn properties.

As mentioned above, to improve the heat resistant property, it is extremely advantageous to combine MBI and copper compounds, but depending on the types of copper compounds used, there is notable corrosive reaction.

The inventors, as a result of detailed study on this phenomenon, found that when inorganic copper salt and M31 are combined, due to their correlation, the corrosive reaction occurs. That is, no corrosive reaction occurs by MBI alone, and also a very little corrosive action occurs by inorganic copper salt alone, and there is no real trouble in practice, but when these two materials exist together, then the notable corrosive reaction beings to occur. And also, it was discovered that in this phenomenon, copper itself is not involved, but negative ions originated from copper salt and MB] are involved.

Accordingly, to prevent such corrosive reaction using MBI, the chemical compounds to be used together with MBI must not have in the first place negative ions which induce corrosive reaction, and also have sufficiently high solubility for polyamides.

Based on these findings, the inventors made intensive study on polyamide compositions to improve frequent drip occurence and corrosion which are flaws for the MB] containing polyamide composites, moreover, the inventors studied the polyamide compositions which wouldnot'lose its excellent heat resistant property because of having MBI in its composites. As a result of the study, the inventors found that polyamide compositions which contain M81 and copper salt and magnesium salt of specific compounds satisfy conditions described above, and arrived to this invention.

SUMMARY OF THE INVENTION This invention is the polyamide composition which is characterized by containing a) 2- mercaptobenzimidazol, b) 2-mercaptobenzimidazol copper salt and/or organic acid copper salt, along with c) Z-mercaptobenzimiclazol magnesium salt, organic acid magnesium salt and/or 8-hydroxyquinoline magnesium salt.

Polyamide as mentioned in this invention covers all fiber-forming type polyamide obtainable from polymerizable diamine and dibasic acids, monoamine mono-carboxy acid, or'similar amide forming derivatives. These polyamidesinclude not .only nylon 6, 66, 610, etc. of aliphatic polyamides, but also include polyamides which have aromatic ring, aliphatic ring, and heterocyclic ring in their main chains,for example, polyhexamethylene isophthalimide. In this invention, among these polyamides, nylon 6, nylon 66, and their copolymers are particularly best suitable for this invention.

MBI-copper salt to be used as (b) component as given in this invention could be obtained from a regular method, for example, by reaction between the reaction product of MBI and caustic soda and halogenated copper. However, it is most necessary to rinse sufficiently so that there would not be any corrosive provoking negative ions remaining in the MBl-copper salt.

As examples on organic acid copper salt, there are acetic acid copper, valeric acid copper, capric acid copper, lauric acid copper, stearic acid copper, oleic acid copper, benzoic acid copper, etc. The quantity of these copper compounds to be used for polyamides ranges from about 10 to about 500 ppm based on the metallic copper conversion calculation.

It is not expected to improve any further against heat resistance even used more than 500 ppm, and also for less than 10 ppm the heat resistance improvement is particularly not expected. The quantity of MB] of (a) component to be used in combination with (b) component for polyamide is in'the range of from about 0.01 to about 5 weight percent, preferably 0.1 to 2.0 weight percent. For the quantity less than 0.01 percent, the heat resistant improvement is insufficient, and, on the other hand, quantity more than 5 weight percent use would make the effect of further improvement unrecognizable.

From polyamide composites containing (a) and (b) components, polyamide compositions which possess heat resistant property at high temperatures and yet resist to corrosion could be obtained, but these compositions have poor spinnability and susceptible to drips. These drips could be reduced by using above (a) and (b) components along with magnesium compound. but magnesium compound and a copper compound require absence of corrosion type negative ions, and also possess sufficient solubility for polyamides. The (c) components to be used in this invention were discovered as a result of several examinations which satisy conditions as magnesium compound, and they are MBI- magnesium salt, S-hydroxy quinoline magnesium salt, and organic acid magnesium salt.

MBl-magnesium salt and 8-hydroxy quinoline magnesium salt to be applied as (c) component in this invention could be obtained from regular methods, for example, by chemical process of chemical reaction products with caustic soda and halogenated magnesium. However, for either case, it is necessary to rinse out sufficiently to remove corrosion type negative ions completely. Also, as for organic acid magnesium salt, the magnesium salt types could be acetic acid, propimersed for 6 days at 90C. into 200 ml chip extract which has been extracted for 10 hours with 98C. pure water in a solution ratio of 3 which extract is condensed to 50 to.1 (by volume).

onic acid, butyric acid, valeric acid, lauric acid, myris- Also, intrinsic viscosity is a value measured in mtic acid, palmitic acid, stearic acid, oleic acid, benzoic cresol at 35C.

acid, phthalic acid, etc. The quantit of these ma nesium compounds to be applied on pcilyamides is in the EXAMPLE 1 range of about 5 to 150 pp based n h lli m g- Obtained 1.55 intrinsic viscosity polyamide from a nesium conversion calculation. Using less than 5 ppm, v nti nal polymerization method with addition of one cannot expect to prevent drips, and on the other 0,3 percent each of MB] and 150 ppm of copper comhand, using more than 150 ppm, the further improvepound (analyzed as copper metal) and 40 ppm of magmem for its ejffecfivehess is not expected nesium compound (analyzed as magnesium metal) as The CQmPQShiOhS described in this invention have shown in the following table into epsilon-caprolactam several optional methods for preparation. For example, d i h manufacturing f nylon 6 more than one Components of aforementioned This polyamide composition was spun at 275C. spinand Components Could he added to polyamide raw ning temperature, 600 m/minute spinning speed using materials hdore Polymerization, during p y a spinnerette which has 24 0.6 mm diameter capillaries tion or to the P Polyamides Containing and takeup wound as undrawn yarn. The obtained fiber and CompOnems disclosed in this invention y had a 210 denier, 8.5 grams per denier tenacity, 11.8 also contain discoloration prevention agent, heat resispercent elongation 10 7 percent b i i water i ktant stabilizing agent, ultraviolet stabilizing agent, elecage ft drawing f h uhdmwn yam at a d i trification prevention agent, polymerization stabilizing f 4.6 times with use f a i i di id i d agent, brightening agent, 190C. hot plate at speed of 300 m/minute.

The polyamide Composites disclosed in this invention 25 The results of heat stability, corrosion characteristic, have, in Spite of M31 Content, excellent p Prevention and measurement on drip occurrence time is shown in Properties because of its having Particular pp Table l. The drip occurrence time is the time at and magnesium salt, have not shown corrosion on varihi h a d i Occurs after Starting i i (Th d i Ous polyamide Process equipment, and, in addition, occurrence time in the next example is also the same tain heat resistant property characteristics of MBI cond fi iti taining poly mi Composites Without losing even For comparison, various polyamide composites were slightly. obtained (intrinsic viscosity of polyamide and drawing conditions are the same as above described example) DESCRIPTION OF THE PREFERRED from (1) case of adding MB] only, (2) case of adding EMBODIMENTS 35 MBl and MBI-copper salt (3) case of adding M81 and In the following actual examples are given. In these inorganic copper salt and magnesium salt (4) case of examples, the percent indicating quantity applied is adding inorganic copper salt and magnesium salt and meant weight percent applied, and heat resistant performed the same measurement which results were property is measurement obtained from the filament listed in Table 1.

TABLE l Heat Stability Copper Magnesium Drip Corrosion Compound Compound Tenacity Elongation Occurrence Reduction MBl 150 ppm as 40 ppm as Retention Retention Time Quantity Example Copper Metal Magnesium Metal Ratio ('7!) Ratio (7:) (Hours) (Grams) Example of This 0.3 MB] Copper Magnesium 100 lOO 72 0 Invention Salt Acetate Examples 03 M81 Copper 100 100 30 0 for Salt Comparison 0.3 CuCl Magnesium 100 100 72 60 Acetate* 0 CuCI. MgCl 91 66 2 *M tocmcot,

before and after treating the filament at 180C. (in air) for 4 hours and used filament strength retention ratio (strength after heat treatment/strength before heat treatment X percent) and filament elongation retention ratio (elongation after heat treatment/elongation before heat treatment X 100 percent) as a scale for measuring heat resistant property.

The corrosion property" is determined by weight loss of 60 gram stainless steel test'piece (SUS 27) im- From the above table, it can be clearly understood that the polyamide composite from this invention was shown to be far superior in heat stability, effective in prevention of drips and resistance to corrosion.

EXAMPLE 2 To investigate the effect of various copper compound and magnesium compound combination in the actual example 1, method, polyamide compositions were obtained from varying combinations of both compounds as shown in Table 2, and the effect of each cases test results were shown in Table 2, the MB] in each case of combination was 0.3 percent, copper was 150 ppm,

the improvement comprising said polyamide also containing c. from about 5 parts per million to about 150 parts per million, analyzed as magnesium metal, of a msgneslum was PP and intrinsic Viscosity of p 5 compound selected from the group consisting of "P was Spmmng and f' g of y was the magnesium salt of 2-mercaptobenzimidazol, ried as exactly the same conditlons in actual Example and g hydroxyquinoline magnesium Salt 2. The polyamide composition of claim 1 wherein the TABLE 2 Heat Stability Drip Corrosion Tenacity Elongation Occurrence Reduction Copper Magnesium Retention Retention Time Quantity Compound Compound Ratio (/2) Ratio (/1) (Hours) (Grams) Copper Magnesium 100 I 72 0 Acetate* Acetate** Copper Mg salt of 100 I00 72 0 Acetate* MBl MBl Copper Mg salt of 100 100 72 0 Salt B-hydroxy quinoline Copper Magnesium 100 l ()0 72 0 Benzoate Stearatc *CulOCH COy **Mg(OCH;,CO)-

EXAMPLE 3 2-mercaptobenzimidazol is present in an amount of A 1.60 intrinsic viscosity polymer was obtained with adding MBI, MBl copper salt and magnesium acetate to the 6.6 salt during manufacturing of nylon 6.6 with a conventional polymerization. This polymer contained 0.25 percent of MBI, 130 ppm of copper, 30 ppm of magnesium. The spun and drawn yarn from this polyamide composite had the heat stability of 100 percent in both tenacity retention ratio and elongation retention ratio and drip occurrence time was 66 hours, also there were no noticeable corrosion characteristics.

We claim:

1. In a composition consisting essentially of a polyamide, containing, based on the weight of said polyamide,

a. from about 0.01 weight percent to about 5 weight percent 2-mercaptobenzimidazol, and

b. from about parts per million to about 500 parts per million, analyzed as copper metal, of a compound selected from the group consisting of the copper salt of Z-mercaptobenzimidazol and an organic acid copper salt,

from about 0.1 weight percent to about 2 weight percent.

3. ln a method to reduce drip occurrence during spinning of a heat resistant, corrosion resistant polyamide composition, containing, based on the weight of said polyamide,

a. from about 0.01 weight percent to about 5 weight percent 2-mercaptobenzimidazol, and

b. from about 10 parts per million to about 500 parts per million, analyzed as copper metal, of a compound selected from the group consisting of the copper salt of 2-mercaptobenzimidazol and an organic acid copper salt,

the improvement comprising adding to said polyamide, prior to spinning,

c. from about 5 parts per million to about parts per million, analyzed as magnesium metal, of a compound selected from the group consisting of the magnesium salt of 2 mercaptobenzimidazol,

and 8-hydroxyquinoline magnesium salt. 

1. In a composition consisting essentially of a polyamide, containing, based on the weight of said polyamide, a. from about 0.01 weight percent to about 5 weight percent 2-mercaptobenzimidazol, and b. from about 10 parts per million to about 500 parts per million, analyzed as copper metal, of a compound selected from the group consisting of the copper salt of 2-mercaptobenzimidazol and an organic acid copper salt, the improvement comprising said polyamide also containing c. from about 5 parts per million to about 150 parts per million, analyzed as magnesium metal, of a compound selected from the group consisting of the magnesium salt of 2-mercaptobenzimidazol, and 8-hydroxyquinoline magnesium salt.
 1. IN A COMPOSITION CONSISTING ESSENTIALLY OF A POLYAMIDE, CONTAINING, BASED ON THE WEIGHT OF SAID POLYAMIDE, A. FROM ABOUT 0.01 WEIGHT PERCENT TO ABOUT 5 WEIGHT PERCENT 2-MERCAPTOBENZIMIDAZOL, AND B. FROM ABOUT 10 PARTS PER MILLION TO ABOUT 500 PARTS PER MILLION, ANALYZED AS COPPER METAL, OF A COMPOUND SELECTED FROM THE GROUP CONSISTING OF THE COPPER SALT OF 2MERCAPTOBENZIMIDAZOL AND AN ORGANIC ACID COPPER SALT, THE IMPROVEMENT COMPRISING SAID POLYAMIDE ALSO CONTAINING C. FROM ABOUT 5 PARTS PER MILLION TO ABOUT 150 PARTS PER MILLION, ANALYZED AS MAGNESIUM METAL, OF A COMPOUND SELECTED FROM THE GROUP CONSISTING OF THE MAGNESIUM SALT OF 2-MERCAPTOBENZIMIDAZOL, AND 8-HYDROXYQUINOLINE MAGNESIUM SALT.
 2. The polyamide composition of claim 1 wherein the 2-mercaptobenzimidazol is present in an amount of from about 0.1 weight percent to About 2 weight percent. 